ISIS Internet Draft Jean-Philippe Vasseur Stefano Previdi Mike Shand Les Ginsberg Cisco Systems Document: draft-vasseur-isis-caps-01.txt Expires: August 2004 February 2004 IS-IS extensions for advertising router information draft-vasseur-isis-caps-01.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [i]. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract This document defines a new optional IS-IS TLVs named CAPABILITY, formed of multiple sub-TLVs, which allows a router to announce its capabilities within an IS-IS level or the entire routing domain. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [ii]. Vasseur et al. Expires û August 2004 [Page 1] draft-vasseur-isis-caps-01.txt February 2004 Table of Contents 1. Introduction...................................................2 Field Code 2. IS-IS CAPABILITY TLV...........................................2 Field Code 3. Element of procedure...........................................3 Field Code 4. Interoperability with routers not supporting the capability TLV.4 Field Code 5. Security considerations........................................4 6. Acknowledgment.................................................4 Field Code 7. Intellectual Property Considerations...........................4 Field Code 8. References.....................................................5 Field Code Normative references..............................................5 Field Code Informative references............................................5 9. Author's Addresses.............................................5 Field Code Field Code Field Code 1. Introduction There are several situations where it is useful for the IS-IS routers to learn the capabilities of the other routers of their IS-IS level, area or routing domain. Some applications are described in [IS-IS-TE- CAP] but for the sake of illustration, one can briefly describes three of them related to MPLS Traffic Engineering. - Path Computation Element (PCE) discovery: in several situations, the Traffic Engineering Label Switched (TE LSP) path is computed by a Label Switch Router (LSR) it is not the head-end for (e.g an ABR or an ASBR respectively in the context of inter-area and inter-AS MPLS TE ([INTER-AREA-AS]). In such a case, having the ability to discover the capability of an router to act as a PCE is extremely useful in term of ease of operation, capacity to react to PCE failure, load sharing between a set of PCEs, etc - Mesh-group: the setting up of a mesh of TE LSPs requires some significant configuration effort. [IS-IS-TE-CAP] proposes an auto- discovery mechanism whereby every LSR of a mesh advertises its mesh-group membership by means of IS-IS extensions. - Point to Multi-point TE LSP (P2MP LSP). A specific sub-TLV ([IS- IS-TE]) allows an LSR to advertise its capabilities to be a ôbranch nodeö of a P2MP TE LSP (see [P2MP] and [P2MP-reqs]). The capability mentioned above lead to the specification of specific TLVs carried within the CAPABILITY TLV defined in this document. Note that the examples above are provided for the sake of illustration. This document proposes a generic capability advertisement mechanism not limited to MPLS Traffic Engineering. 2. IS-IS CAPABILITY TLV Vasseur et al. Expires û August 2004 [Page 2] draft-vasseur-isis-caps-01.txt February 2004 The IS-IS CAPABILITY TLV is composed of 1 octet for the type, 1 octet specifying the TLV length, 1 octet of bit flags and a variable length value field, starting with 4 octets of Router ID. CODE: To be assigned by IANA LENGTH: Variable (1 octet) VALUE: Router ID (4 octets) Flags (1 octet) Set of optional sub-TLVs (0-249 octets) Flags +-+-+-+-+-+-+-+-+ |S|U| | +-+-+-+-+-+-+-+-+ Currently two bit flags are defined. S bit: when set, the IS-IS CAPABILITY TLV MUST be flooded across the entire routing domain; hence, according to the element of procedure defined in section 3, the CAPABILITY TLV MUST be leaked between IS-IS levels or multiple areas of the same IS-IS level by L1L2 routers that support the CAPABILITY TLV. U bit: the U bit MUST be set each time the CAPABILITY TLV is leaked into another IS-IS level or another area of the same IS-IS level. When set, the U bit MUST not be changed by any other router. The CAPABILITY TLV is OPTIONAL. As specified in section 3, more than one CAPABILITY TLVs may be present. 3. Element of procedure In case of capabilities with different scopes, a router MUST include two CAPABILITY TLVs, each TLV carrying the set of sub-TLVs with the same flooding scope. For instance, if a router advertises two capabilities C1 and C2 respectively with an area/level scope and routing domain scope, C1 and C2 being specified by their respective sub-TLV(s), the router MUST include two CAPABILITY TLVs: - One CAPABILITY TLV with the S flag cleared carrying the sub- TLV(s) relative to C1. The CAPABILITY TLV MUST NOT be leaked into other level or areas of the same level. - One CAPABILITY TLV with the S flag set carrying the sub-TLV(s) relative to C2. This CAPABILITY TLV MUST be leaked into other IS-IS levels or areas or the same level after having set the U bit. Other sub-TLVs MUST be unchanged during the leaking procedure. Vasseur et al. Expires û August 2004 [Page 3] draft-vasseur-isis-caps-01.txt February 2004 A router receiving a CAPABILITY TLV with the U flag set MUST NOT leak the CAPABILITY TLV into another ISIS level or areas. This prevents TLV looping. 4. Interoperability with routers not supporting the capability TLV. There is no interoperability issue as a router not supporting the CAPABILITY TLV MUST just silently ignore the TLV(s) and continue the LSP processing. If just a subset of the sub-TLVs carried within the CAPABILITY TLV are supported, then the not supported sub-TLV MUST be silently ignored. 5. Security considerations No new security issues are raised in this document. 6. Acknowledgment The authors would like to thank Jean-Louis Le Roux and Paul Mabey for their useful comments. 7. Intellectual Property Considerations The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. The IETF has been notified of intellectual property rights claimed in regard to some or all of the specification contained in this document. For more information consult the online list of claimed rights. Vasseur et al. Expires û August 2004 [Page 4] draft-vasseur-isis-caps-01.txt February 2004 8. References Normative references [RFC] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels," RFC 2119. [IS-IS] "Intermediate System to Intermediate System Intra-Domain Routeing Exchange Protocol for use in Conjunction with the Protocol for Providing the Connectionless-mode Network Service (ISO 8473)", ISO 10589. [IS-IS-IP] Callon, R., RFC 1195, "Use of OSI IS-IS for routing in TCP/IP and dual environments", RFC 1195, December 1990. [ISIS-TE] Li, T., Smit, H., "IS-IS extensions for Traffic Engineering", draft-ietf-isis-traffic-04.txt (work in progress) Informative references [IS-IS-TE-CAP] JP Vasseur, S. Previdi, JL. Le Roux, ôIS-IS MPLS Traffic Engineering capabilitiesö, draft-vasseur-ccamp-isis-te-caps- 00.txt, work in progress. [P2MP] S. Yasukawa et al. ½ Extended RSVP TE for point-to-multipoint LSP tunnelsö, draft-yasukawa-mpls-rsvp-p2mp-03.txt, work in progress. [P2MP-reqs] S. Yasukawa et al. ½ Requirements for point to multipoint extension to RSVP ©, draft-ietf-mpls-p2mp-requirement-01.txt, work in progress. [INTER-AREA-AS] Vasseur and Ayyangar, ôInter-area and Inter-AS MPLS Traffic Engineeringö, draft-vasseur-ayyangar-inter-area-AS-TE-00.txt, work in progress. 9. Author's Addresses Jean-Philippe Vasseur CISCO Systems, Inc. 300 Beaver Brook Boxborough, MA 01719 USA Email: jpv@cisco.com Field Code Stefano Previdi CISCO Systems, Inc. Vasseur et al. Expires û August 2004 [Page 5] draft-vasseur-isis-caps-01.txt February 2004 Via Del Serafico 200 00142 - Roma ITALY Email: sprevidi@cisco.com Field Code Mike Shand Cisco Systems 250 Longwater Avenue, Reading, Berkshire, RG2 6GB UK Phone: +44 208 824 8690 Email: mshand@cisco.com Field Code Les Ginsberg Cisco Systems 510 McCarthy Blvd. Milpitas, Ca. 95035 USA Email: ginsberg@cisco.com Field Code Full Copyright Statement Copyright (C) The Internet Society (2004). All Rights Reserved. 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